Method for preparing chitosan fiber from amino acid ionic liquid aqueous solution

Abstract

The invention provides a method for preparing chitosan fibers from an amino acid ionic liquid aqueous solution, and belongs to the technical field of chitosan resource utilization. Chitosan is dissolved in an aqueous solution of amino acid ionic liquid to prepare a spinning solution, and the chitosan fiber is prepared through defoaming, filtering and wet spinning. The amino acid ionic liquid aqueous solution used in the invention can realize rapid dissolution of high molecular weight chitosan at room temperature, the dissolution condition is mild, the dissolution time is greatly shortened, the prepared chitosan fiber has good performance, the breaking strength is 1.1-2.0 cN / dtex, the elongation is 2.1-3.4%, and the chitosan fiber can be applied to the fields of biomedicine, environmental protection, textile industry and the like.

Description

Technical Field

[0001] The invention relates to the technical field of chitosan resource utilization, in particular to a method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution. Background Art

[0002] Chitosan is a common natural cationic alkaline polysaccharide, which is widely found in the exoskeletons of crustaceans such as shrimps and crabs, and in the cell walls of fungi and algae. Chitosan fibers prepared from chitosan have become one of the research hotspots for medical materials such as medical sutures, tissue repair and bone repair due to its excellent biocompatibility, biodegradability, and antibacterial and anti-inflammatory properties. However, chitosan has strong intramolecular / intermolecular hydrogen bonds, making it difficult to dissolve in water and most organic solvents, which greatly limits its high-value application.

[0003] Traditional chitosan dissolution methods usually require the use of dilute acid or strong alkali. Chinese patent CN102199810B discloses a method for preparing chitosan fiber, which uses lithium hydroxide-sodium hydroxide-urea system as solvent to dissolve chitosan. Although the prepared fiber has good mechanical properties, the freeze-thaw cycle required for the strong alkali system to dissolve is energy-intensive, which increases production costs. Chinese patent CN101250759B discloses a medical chitosan fiber and a method for preparing it, which discloses a method for dissolving chitosan and preparing chitosan fiber using acetic acid as solvent. The mechanical properties of the obtained chitosan fiber are poor and cannot meet the requirements of practical applications. In recent years, ionic liquids, as an environmentally friendly solvent, have been widely used to dissolve biomacromolecules such as chitosan, cellulose, and keratin because of their advantages such as high thermal stability, low volatility, and designability. Chinese patent CN102168323A discloses a method for preparing chitosan and chitin functional materials using imidazolyl ionic liquid as solvent. Although chitosan fibers with strong mechanical properties can be prepared, the dissolution process has disadvantages such as high dissolution temperature, long dissolution time, high system viscosity, and low molecular weight of dissolved chitosan (300-600 kDa). At the same time, halogen-containing ionic liquids such as 3-butyl-4-methylthiazolium chloride ([BMTHI]Cl) and 3-butyl-4-methylthiazolium bromide ([BMTHI]Br) can also cause serious corrosion to equipment, reduce the service life of spinning equipment, and are difficult to use for large-scale industrial production. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution, so as to solve the technical problems in the preparation of chitosan fiber, such as high solvent cost and strong corrosiveness, high energy consumption in the chitosan dissolution process, long dissolution time, high system viscosity and low molecular weight of dissolved chitosan.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution, comprising the following steps:

[0007] 1) mixing chitosan with an aqueous solution of an amino acid nitrate ionic liquid, dissolving the chitosan under mechanical stirring conditions to obtain an ionic liquid-chitosan solution;

[0008] 2) The obtained ionic liquid-chitosan solution is subjected to vacuum degassing, filtered, and then sequentially spun, drawn, washed, oiled, and dried to obtain chitosan fibers.

[0009] Furthermore, the preparation method of the amino acid nitrate ionic liquid is:

[0010] After the amino acid and nitric acid are mixed in equal molar ratios, the mixture is heated at 50-70° C. for 10-14 hours to obtain the amino acid nitrate ionic liquid.

[0011] Furthermore, the amino acid comprises one or more of glycine, L-proline, L-isoleucine, L-serine and L-leucine, and the mass concentration of the nitric acid is 60-70%.

[0012] Furthermore, the concentration of the aqueous solution of the amino acid nitrate ionic liquid is 4-6 wt %.

[0013] Furthermore, the molecular weight of the chitosan is 900-1050 kDa, the degree of deacetylation is 85%, the moisture content is ≤5%, and the ash content is <0.5%.

[0014] Furthermore, the speed of the mechanical stirring is 100-150 r / min, the dissolution temperature is 25-30° C., and the dissolution time is 10-180 min;

[0015] The concentration of the ionic liquid-chitosan solution is 5-6wt%, and the viscosity at 30°C is 20-50 Pa·s.

[0016] Furthermore, the spinning is wet spinning, and the coagulation bath is 3-6wt% Na 2 CO 3 -Ethanol, 3-6wt% Na 2 SO 3 -ethanol, 3-6wt% NaOH-ethanol and 3-6wt% sodium tripolyphosphate, the temperature of the coagulation bath is 20-40°C, and the water washing temperature is 40-60°C.

[0017] Furthermore, the chitosan is sequentially treated with alkali washing, water washing and drying before dissolving, specifically:

[0018] The chitosan raw material is mixed with a 4 wt % NaOH solution, and alkali washed at 30° C. for 4 h at a solid-liquid mass ratio of 1:7, and then the washed chitosan raw material is dried at 60-80° C. for 8-12 h.

[0019] Furthermore, the breaking strength of the chitosan fiber is 1.1-2.0 cN / dtex, and the elongation is 2.1%-3.4%.

[0020] Beneficial effects of the present invention:

[0021] (1) The amino acid nitrate ionic liquid used in the present invention has the advantages of one-step synthesis, low price, and recyclability;

[0022] (2) using an ionic liquid aqueous solution of glycine nitrate, L-proline nitrate, L-isoleucine nitrate, L-serine nitrate and L-leucine nitrate as a solvent, chitosan can be efficiently dissolved at room temperature to obtain an ionic liquid-chitosan solution;

[0023] (2) The present invention successfully prepared chitosan fibers with excellent mechanical properties (tensile strength of 1.1-2.0 cN / dtex, elongation of 2.1%-3.4%). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structural formula of the amino acid nitrate ionic liquid in Examples 1 to 10 of the present invention. DETAILED DESCRIPTION

[0025] The present invention provides a method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution, comprising the following steps:

[0026] 1) mixing chitosan with an aqueous solution of an amino acid nitrate ionic liquid, dissolving the chitosan under mechanical stirring conditions to obtain an ionic liquid-chitosan solution;

[0027] 2) The obtained ionic liquid-chitosan solution is subjected to vacuum degassing, filtered, and then sequentially spun, drawn, washed, oiled, and dried to obtain chitosan fibers.

[0028] In the present invention, the preparation method of the amino acid nitrate ionic liquid is:

[0029] After the amino acid and nitric acid are mixed in an equal molar ratio, the mixture is heated at 50-70° C. for 10-14 hours to obtain an amino acid nitrate ionic liquid; preferably, after the amino acid and nitric acid are mixed in an equal molar ratio, the mixture is heated at 60° C. for 12 hours to obtain an amino acid nitrate ionic liquid.

[0030] In the present invention, the amino acid comprises one or more of glycine, L-proline, L-isoleucine, L-serine and L-leucine, and the mass concentration of the nitric acid is 60-70%, preferably 65%.

[0031] In the present invention, the concentration of the aqueous solution of the amino acid nitrate ionic liquid is 4-6 wt%, preferably 5 wt%.

[0032] In the present invention, the molecular weight of the chitosan is 900-1050 kDa, the degree of deacetylation is 85%, the moisture content is ≤5%, and the ash content is <0.5%; the molecular weight of the chitosan is preferably 1006-1025 kDa.

[0033] In the present invention, the speed of the mechanical stirring is 100-150 r / min, preferably 110-140 r / min, and more preferably 120-130 r / min; the dissolution temperature is 25-30°C, and the dissolution time is 10-180 min, preferably 50-120 min, and more preferably 60-100 min.

[0034] In the present invention, the concentration of the ionic liquid-chitosan solution is 5-6wt%, preferably 5.5wt%; the viscosity at 30°C is 20-50Pa·s, preferably 30-40Pa·s, and more preferably 35Pa·s.

[0035] In the present invention, the spinning is wet spinning, and the coagulation bath is 3-6wt% Na 2 CO 3 -Ethanol, 3-6wt% Na 2 SO 3 -ethanol, 3-6wt% NaOH-ethanol and 3-6wt% sodium tripolyphosphate, preferably 3-6wt% Na 2 CO 3 -ethanol; the temperature of the coagulation bath is 20 to 40°C, preferably 25 to 30°C; the water washing temperature is 40 to 60°C, preferably 45 to 55°C, and more preferably 50°C.

[0036] In the present invention, the chitosan is sequentially treated with alkali washing, water washing and drying before being dissolved, specifically:

[0037] The chitosan raw material is mixed with a 4 wt % NaOH solution, and alkali washed at 30° C. for 4 h at a solid-liquid mass ratio of 1:7, and then the washed chitosan raw material is dried at 60-80° C. for 8-12 h.

[0038] In the present invention, the breaking strength of the chitosan fiber is 1.1-2.0 cN / dtex, and the elongation is 2.1%-3.4%.

[0039] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0040] Example 1

[0041] A method for mildly preparing chitosan fibers from an amino acid ionic liquid aqueous solution of the present embodiment comprises the following steps:

[0042] (1) The chitosan raw material (molecular weight 900 kDa, deacetylation degree 85%) was pretreated by alkali washing, water washing and drying. The specific method was as follows: chitosan was mixed with 4 wt % NaOH, the solid-liquid mass ratio was 1:7, the treatment temperature was 30 ° C, the treatment time was 4 h, and the treated chitosan was washed with deionized water and dried at 70 ° C for 12 h.

[0043] (2) The pretreated chitosan raw material was mixed with a 4 wt % glycine nitrate aqueous solution at a mass ratio of 1:18, dissolved at a dissolution temperature of 25°C and a mechanical stirring speed of 150 r / min for 60 min, and a transparent ionic liquid-chitosan solution was obtained after degassing, with a viscosity of 50 Pa·s at 30°C.

[0044] (3) The ionic liquid-chitosan solution was squeezed into 4 wt% Na2O3 at 20 °C through a spinneret with a pore size of 0.2 mm at a pressure of 0.2 MPa. 2 CO 3 The fiber was coagulated in a coagulation bath of 1:1 of ethanol and a spinning rate of 3 m / min and a draft ratio of 1.5. The fiber was washed in deionized water at 40°C and then oiled. The fiber was dried at 60°C to obtain chitosan fiber.

[0045] (4) Through testing, the breaking strength of chitosan fiber is 1.1 cN / dtex and the elongation is 3.4%.

[0046] Example 2

[0047] A method for mildly preparing chitosan fibers from an amino acid ionic liquid aqueous solution of the present embodiment comprises the following steps:

[0048] (1) The chitosan raw material (molecular weight 900 kDa, deacetylation degree 85%) was pretreated by alkali washing, water washing and drying. The specific method was as follows: chitosan was mixed with 4 wt % NaOH, the solid-liquid mass ratio was 1:7, the treatment temperature was 30 ° C, the treatment time was 4 h, and the treated chitosan was washed with deionized water and dried at 70 ° C for 12 h.

[0049] (2) The pretreated chitosan raw material was mixed with a 4 wt % proline nitrate aqueous solution at a mass ratio of 1:20, dissolved at a dissolution temperature of 25° C. and a mechanical stirring speed of 130 r / min for 30 min, and a transparent ionic liquid-chitosan solution was obtained after degassing, with a viscosity of 40 Pa·s at 30° C.

[0050] (3) The ionic liquid-chitosan solution was squeezed into 4 wt% Na2O3 at 20 °C through a spinneret with a pore size of 0.2 mm at a pressure of 0.2 MPa. 2 CO 3 The fiber was coagulated in a coagulation bath of 1:1 of ethanol and a spinning rate of 3 m / min and a draft ratio of 1.5. The fiber was washed in deionized water at 40°C and then oiled. The fiber was dried at 60°C to obtain chitosan fiber.

[0051] (4) Through testing, the breaking strength of chitosan fiber is 1.4 cN / dtex and the elongation is 2.8%.

[0052] Example 3

[0053] A method for mildly preparing chitosan fibers from an amino acid ionic liquid aqueous solution of the present embodiment comprises the following steps:

[0054] (1) The chitosan raw material (molecular weight of 1006 kDa, degree of deacetylation of 85%) was pretreated by alkali washing, water washing and drying. The specific method was as follows: chitosan was mixed with 4 wt % NaOH, the solid-liquid mass ratio was 1:7, the treatment temperature was 30 ° C, the treatment time was 4 h, and the treated chitosan was washed with distilled water and dried at 70 ° C for 12 h.

[0055] (2) The pretreated chitosan raw material was mixed with a 4 wt % glycine nitrate aqueous solution at a mass ratio of 1:18, dissolved at a temperature of 25° C. and a mechanical stirring speed of 110 r / min for 2 h, and a transparent ionic liquid-chitosan solution was obtained after degassing with a viscosity of 50 Pa·s.

[0056] (3) The ionic liquid-chitosan solution was squeezed into a coagulation bath of 4 wt% NaOH:ethanol = 1:1 at 20°C through a spinneret with a pore size of 0.2 mm at a pressure of 0.2 MPa for coagulation molding. The spinning rate was controlled to be 3 m / min and the draw ratio was 1.5. The fibers were washed in deionized water at 40°C and then oiled. The fibers were dried at 60°C to obtain chitosan fibers.

[0057] (4) Through testing, the breaking strength of chitosan fiber is 1.1 cN / dtex and the elongation is 3.4%.

[0058] Example 4

[0059] A method for mildly preparing chitosan fibers from an amino acid ionic liquid aqueous solution of the present embodiment comprises the following steps:

[0060] (1) The chitosan raw material (molecular weight of 1025 kDa, degree of deacetylation of 85%) was pretreated by alkali washing, water washing and drying. The specific method was as follows: chitosan was mixed with 4 wt % NaOH, the solid-liquid mass ratio was 1:7, the treatment temperature was 30 ° C, the treatment time was 4 h, and the treated chitosan was washed with distilled water and dried at 70 ° C for 12 h.

[0061] (2) The pretreated chitosan raw material was mixed with a 4 wt % isoleucine nitrate aqueous solution at a mass ratio of 1:25, dissolved at a temperature of 25°C and a mechanical stirring speed of 100 r / min for 2 h, and a transparent ionic liquid-chitosan solution was obtained after degassing, with a viscosity of 30 Pa·s at 30°C.

[0062] (3) The ionic liquid-chitosan solution was squeezed into a coagulation bath of 4 wt% sodium tripolyphosphate: ethanol = 1:1 at 20°C through a spinneret with a pore size of 0.2 mm at a pressure of 0.2 MPa to coagulate and form the fiber. The spinning rate was controlled to be 3 m / min and the draw ratio was 1.5. The fiber was washed in deionized water at 40°C and then oiled. The fiber was dried at 60°C to obtain chitosan fiber.

[0063] (4) Through testing, the breaking strength of chitosan fiber is 1.5 cN / dtex and the elongation is 2.6%.

[0064] Example 5

[0065] A method for mildly preparing chitosan fibers from an amino acid ionic liquid aqueous solution of the present embodiment comprises the following steps:

[0066] (1) The chitosan raw material (molecular weight of 1050 kDa, degree of deacetylation of 85%) was pretreated by alkali washing, water washing and drying. The specific method was as follows: chitosan was mixed with 4 wt % NaOH, the solid-liquid mass ratio was 1:7, the treatment temperature was 30 ° C, the treatment time was 4 h, and the treated chitosan was washed with deionized water and dried at 70 ° C for 12 h.

[0067] (2) The pretreated chitosan raw material was mixed with a 4 wt% leucine nitrate aqueous solution at a mass ratio of 1:25, dissolved at a temperature of 25°C and a mechanical stirring speed of 100 r / min for 2 h, and a transparent ionic liquid-chitosan solution was obtained after degassing, with a viscosity of 25 Pa·s at 30°C.

[0068] (3) The ionic liquid-chitosan solution was squeezed into 4 wt% Na2O3 at 20 °C through a spinneret with a pore size of 0.2 mm at a pressure of 0.2 MPa. 2 CO3 The fiber was coagulated in a coagulation bath of 1:1 of ethanol and a spinning rate of 3 m / min and a draft ratio of 1.5. The fiber was washed in deionized water at 40°C and then oiled. The fiber was dried at 60°C to obtain chitosan fiber.

[0069] (4) Through testing, the breaking strength of chitosan fiber is 1.9 cN / dtex and the elongation is 3.1%.

[0070] Example 6

[0071] A method for mildly preparing chitosan fibers from an amino acid ionic liquid aqueous solution of the present embodiment comprises the following steps:

[0072] (1) The chitosan raw material (molecular weight of 1050 kDa, degree of deacetylation of 85%) was pretreated by alkali washing, water washing, drying and the like; the specific method was as follows: chitosan was mixed with 4 wt % NaOH, the solid-liquid mass ratio was 1:7, the treatment temperature was 30 ° C, the treatment time was 4 h, the treated chitosan was washed with deionized water and then dried at 70 ° C for 12 h.

[0073] (2) The pretreated chitosan raw material was mixed with a 4 wt % isoleucine nitrate aqueous solution at a mass ratio of 1:18, dissolved at a temperature of 25°C and a mechanical stirring speed of 100 r / min for 2 h, and a transparent ionic liquid-chitosan solution was obtained after degassing, with a viscosity of 50 Pa·s at 30°C.

[0074] (3) The ionic liquid-chitosan solution was squeezed into 4 wt% Na2O3 at 20 °C through a spinneret with a pore size of 0.2 mm at a pressure of 0.2 MPa. 2 SO 4 The fiber was coagulated in a coagulation bath of 1:1 of ethanol and a spinning rate of 3 m / min and a draft ratio of 1.5. The fiber was washed in deionized water at 40°C and then oiled. The fiber was dried at 60°C to obtain chitosan fiber.

[0075] (4) Through testing, the breaking strength of chitosan fiber is 1.3 cN / dtex and the elongation is 2.9%.

[0076] Example 7

[0077] A method for mildly preparing chitosan fibers from an amino acid ionic liquid aqueous solution of the present embodiment comprises the following steps:

[0078] (1) The chitosan raw material (molecular weight of 1025 kDa, degree of deacetylation of 85%) was pretreated by alkali washing, water washing and drying. The specific method was as follows: chitosan was mixed with 4 wt % NaOH, the solid-liquid mass ratio was 1:7, the treatment temperature was 30 ° C, the treatment time was 4 h, and the treated chitosan was washed with deionized water and dried at 70 ° C for 12 h.

[0079] (2) The pretreated chitosan raw material was mixed with a 4 wt % proline nitrate aqueous solution at a mass ratio of 1:23, dissolved at a temperature of 25°C and a mechanical stirring speed of 100 r / min for 2 h, and a transparent ionic liquid-chitosan solution was obtained after degassing, with a viscosity of 30 Pa·s at 30°C.

[0080] (3) The ionic liquid-chitosan solution was squeezed into 4 wt% Na2O3 at 20 °C through a spinneret with a pore size of 0.2 mm at a pressure of 0.2 MPa. 2 CO 3 The fiber was coagulated in a coagulation bath of 1:1 of ethanol and a spinning rate of 3 m / min and a draft ratio of 1.5. The fiber was washed in deionized water at 40°C and then oiled. The fiber was dried at 60°C to obtain chitosan fiber.

[0081] (4) Through testing, the breaking strength of chitosan fiber is 1.9 cN / dtex and the elongation is 2.0%.

[0082] Example 8

[0083] A method for mildly preparing chitosan fibers from an amino acid ionic liquid aqueous solution of the present embodiment comprises the following steps:

[0084] (1) The chitosan raw material (molecular weight of 900 kDa, degree of deacetylation of 85%) was pretreated by alkali treatment, washing, and drying. The specific method was as follows: chitosan was mixed with 4 wt % NaOH, the solid-liquid mass ratio was 1:7, the treatment temperature was 30 ° C, the treatment time was 4 h, and the treated chitosan was washed with deionized water and dried at 70 ° C for 12 h.

[0085] (2) The pretreated chitosan raw material was mixed with a 4 wt % serine nitrate aqueous solution at a mass ratio of 1:25, dissolved at a temperature of 25°C and a mechanical stirring speed of 150 r / min for 2 h, and a transparent ionic liquid-chitosan solution was obtained after degassing, with a viscosity of 30 Pa·s at 30°C.

[0086] (3) The ionic liquid-chitosan solution was squeezed into 4 wt% Na2O3 at 20 °C through a spinneret with a pore size of 0.2 mm at a pressure of 0.2 MPa. 2 CO 3The fiber was coagulated in a coagulation bath of 1:1 of ethanol and a spinning rate of 3 m / min and a draft ratio of 1.5. The fiber was washed in deionized water at 40°C and then oiled. The fiber was dried at 60°C to obtain chitosan fiber.

[0087] (4) Through testing, the breaking strength of chitosan fiber is 1.8 cN / dtex and the elongation is 2.0%.

[0088] Example 9

[0089] A method for mildly preparing chitosan fibers from an amino acid ionic liquid aqueous solution of the present embodiment comprises the following steps:

[0090] (1) Chitosan raw material (molecular weight 900 kDa, deacetylation degree 85%) was pretreated by alkali treatment, washing and drying; the specific method was as follows: chitosan was mixed with 4 wt% Na 2 CO 3 Mixing, the solid-liquid mass ratio is 1:7, the treatment temperature is 30℃, the treatment time is 4h, and the treated chitosan is washed with deionized water and dried at 70℃ for 12h.

[0091] (2) The pretreated chitosan raw material was mixed with a 4 wt % proline nitrate aqueous solution at a mass ratio of 1:18, dissolved at a temperature of 25°C and a mechanical stirring speed of 150 r / min for 2 h, and a transparent ionic liquid-chitosan solution was obtained after degassing, with a viscosity of 40 Pa·s at 30°C.

[0092] (3) The ionic liquid-chitosan solution was squeezed into 4 wt% Na2O3 at 20 °C through a spinneret with a pore size of 0.2 mm at a pressure of 0.2 MPa. 2 CO 3 The fiber was coagulated in a coagulation bath of 1:1 of ethanol and a spinning rate of 3 m / min and a draft ratio of 1.5. The fiber was washed in deionized water at 40°C and then oiled. The fiber was dried at 60°C to obtain chitosan fiber.

[0093] (4) Through testing, the breaking strength of chitosan fiber is 1.8 cN / dtex and the elongation is 2.1%.

[0094] Example 10

[0095] A method for mildly preparing chitosan fibers from an amino acid ionic liquid aqueous solution of the present embodiment comprises the following steps:

[0096] (1) Chitosan raw material (molecular weight 900 kDa, deacetylation degree 85%) was pretreated by alkali treatment, washing and drying; the specific method was as follows: chitosan was mixed with 4 wt% Na 2 CO 3Mixing, the solid-liquid mass ratio is 1:7, the treatment temperature is 30℃, the treatment time is 4h, and the treated chitosan is washed with deionized water and dried at 70℃ for 12h.

[0097] (2) The pretreated chitosan raw material was mixed with a 4 wt% proline nitrate aqueous solution at a mass ratio of 1:19, dissolved at a temperature of 25°C and a mechanical stirring speed of 120 r / min for 2 h, and a transparent ionic liquid-chitosan solution was obtained after degassing, with a viscosity of 35 Pa·s at 30°C.

[0098] (3) The ionic liquid-chitosan solution was squeezed into 4 wt% Na2O3 at 20 °C through a spinneret with a pore size of 0.2 mm at a pressure of 0.2 MPa. 2 CO 3 The fiber was coagulated in a coagulation bath of 1:1 of ethanol and a spinning rate of 3 m / min and a draft ratio of 1.5. The fiber was washed in deionized water at 40°C and then oiled. The fiber was dried at 60°C to obtain chitosan fiber.

[0099] (4) Through testing, the breaking strength of chitosan fiber is 1.7 cN / dtex and the elongation is 2.2%.

[0100] As can be seen from the above embodiments, the present invention provides a method for preparing chitosan fibers from an amino acid ionic liquid aqueous solution. The amino acid ionic liquid aqueous solution used in the present invention can achieve rapid dissolution of high molecular weight chitosan at room temperature, with mild dissolution conditions, greatly reducing the dissolution time, and the prepared chitosan fibers have good performance, a breaking strength of 1.1 to 2.0 cN / dtex, and an elongation of 2.1 to 3.4%, and can be applied to biomedicine, environmental protection, textile industry and other fields.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution, characterized in that: The following steps are involved: 1) mixing chitosan with an aqueous solution of an amino acid nitrate ionic liquid, dissolving the chitosan under mechanical stirring conditions to obtain an ionic liquid-chitosan solution; 2) The obtained ionic liquid-chitosan solution is subjected to vacuum degassing, filtered, and then sequentially spun, drawn, washed, oiled, and dried to obtain chitosan fibers.

2. The method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution according to claim 1, characterized in that: The preparation method of the amino acid nitrate ionic liquid is as follows: After the amino acid and nitric acid are mixed in equal molar ratios, the mixture is heated at 50-70° C. for 10-14 hours to obtain the amino acid nitrate ionic liquid.

3. The method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution according to claim 2, characterized in that: The amino acid comprises one or more of glycine, L-proline, L-isoleucine, L-serine and L-leucine, and the mass concentration of the nitric acid is 60-70%.

4. The method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution according to any one of claims 1 to 3, characterized in that: The concentration of the aqueous solution of the amino acid nitrate ionic liquid is 4-6 wt %.

5. The method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution according to claim 4, characterized in that: The molecular weight of the chitosan is 900-1050 kDa, the deacetylation degree is 85%, the moisture content is ≤5%, and the ash content is <0.5%.

6. The method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution according to claim 1 or 5, characterized in that: The speed of the mechanical stirring is 100-150 r / min, the dissolution temperature is 25-30° C., and the dissolution time is 10-180 min; The concentration of the ionic liquid-chitosan solution is 5-6wt%, and the viscosity at 30°C is 20-50 Pa·s.

7. The method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution according to claim 6, characterized in that: The spinning is wet spinning, the coagulation bath is one of 3-6wt% Na2CO3-ethanol, 3-6wt% Na2SO3-ethanol, 3-6wt% NaOH-ethanol and 3-6wt% sodium tripolyphosphate, the temperature of the coagulation bath is 20-40°C, and the water washing temperature is 40-60°C.

8. The method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution according to claim 1 or 7, characterized in that: The chitosan is sequentially treated with alkali washing, water washing and drying before dissolving, specifically: The chitosan raw material is mixed with a 4 wt % NaOH solution, and alkali washed at 30° C. for 4 h at a solid-liquid mass ratio of 1:7, and then the washed chitosan raw material is dried at 60-80° C. for 8-12 h.

9. The method for preparing chitosan fiber from an amino acid ionic liquid aqueous solution according to claim 1, characterized in that: The breaking strength of the chitosan fiber is 1.1-2.0 cN / dtex, and the elongation is 2.1%-3.4%.

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